Latching arrangement



Feb. 3, 1970 R. A. JOHNSON 3,493,144

LATCHING ARRANGEMENT Filed Sept. 12, 1968 JMQ Q w BY I United StatesPatent M US. Cl. 221-151 7 Claims ABSTRACT OF THE DISCLOSURE Multiplelatching functions for a longitudinally reciprocable member are producedby an arrangement of interrelated latches. An actuator bar interactswith the latches to provide a desired sequence of latching functions forthe reciprocable member and the actuator bar.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates generally to a latching mechanism, and more particularly thisinvention relates to an arrangement providing multiple latchingfunctions for longitudinally reciprocable trays of a vending machine.

Description of the prior art In many devices only a single cycle ofoperation of a longitudinally reciprocable member is desired uponactuation thereof, and a latching arrangement is employed at a positionadjacent the bottom of the return stroke to engage the member andmaintain it in its retracted position until subsequent actuation. Arepresentative examp e of a device employing such an arrangement is avending machine disclosed in a patent application entitled ArticleVending Apparatus filed concurrently herewith in the names of A. G.Bodoh, O. I. Schwertfeger, and R. A. Johnson and assigned to the sameassignee as this application. In such a device it is desired to have areciprocable delivery mechanism dispense a single article when actuatedby depositing a predetermined amount of money and selecting theparticular type of article desired. Therefore, only a singlereciprocating cycle of the delivery mechanism is desired in conjunctionwith a single actuation thereof, and a latching arrangement is employedto engage the mechanism following its return stroke to prevent multiplereciprocations and consequent multiple dispensing.

Futhermore, the latching functions may also involve other features ofthe overall vending apparatus. For example, an actuating mechanism forthe latching arrangement may also be utilized to lockout other actuatingmechanism to prevent the customer from making another selection. In sucha case, it would be necessary to retain the actuating mechanism in thelockout position until the apparatus is prepared for another vendingcycle to be initiated. Also, the actuating mechanism on the reciprocablemember may be utilized for other lockout functions that would require aparticular sequence of latch operation and positioning of the involvedelements.

It is not possible to achieve the multiple functions described abovewith the conventional single latch biased to engage the deliverymechanism in its retracted position. Also, such an arrangement isparticularly susceptible to the disadvantages of permitting unlimiteddispensing if the bias fails and multiple dispensing if the latch is tooslow in returning to its latching position.

Another approach would be to utilize an electrical control arrangement.This type of arrangement has the obvious disadvantages of being costlyto construct and operate, of being much more cumbersome than mechanical3,493,144 Patented Feb. 3, 1970 arrangements, and of being relativelyunreliable. Further; more, electrical switches could be opened or closedby the subjection of the vending device to physical force, resulting invending without payment or multiple vending.

SUMMARY OF THE INVENTION The latching mechanism of this invention isdesigned to obviate the diificulties noted above with respect to priorart arrangements. Briefly, in the preferred embodiment disclosed hereina stand-by latch lever and a safety latch lever are provided. Each ofthese levers has a hook-shaped head portion mounted on a mounting arm,and a leg portion attached to theend of the mounting arm away from thehead portion and projecting at generally right angles from the mountingarm. The leg portions of the two levers extend generally in the samedirection. The stand-by latch lever and the safety latch lever arecommonly pivoted and are biased toward each other in a scissor fashion.A longitudinally reciprocable member, such as a stud or pin, is biasedto an actuated position and is normally maintained in a normal latchingposition by the hook-shaped head portion of the stand-by latch lever.Reset means are provided to move the reciprocable stud, against itsbias, from its actuated position to an overshoot position, removed fromthe normal latching in a direction opposite to the direction of bias ofthe reciprocable stud member, wherein it is latched by the safety latchlever.

A T-shaped actuator bar slidably mounted for longitudinal reciprocation,having a step intermediate its ends, is biased in a direction oppositeto that of reciprocable stud. The cross piece of the T is at the end ofthe actuator bar adjacent the stand-by and safety latch levers, and thearm of the cross piece closest to the levers is provided with anactuator bar stud projecting outwardly from the actuator bar. The arm ofthe cross piece away from the levers is provided with a notched ear.Movement of the actuator bar against its bias is provided by a suitableactuating arrangement.

An inverted U-shaped actuator lever is pivotally mounted on a pivotthrough its bight, which pivot is at a point removed from the commonpivot of the standby and safety latch levers. The leg of the U-shapedactuator bar farthest removed from the safety and standby latch leversis provided with a hook-shaped portion at its end, which is adapted tolatch the actuator bar by engaging the notched ear thereof. The otherleg of the U, adjacent the stand-by and latch levers, is provided with adepending arm projecting in the path of the reciprocable stud member atan angle with respect to the leg. The actuator bar lever is normallylocated in an unlatched position by engagement between the depending armand the reciprocable stud member.

In utilizing the latching arrangement of this invention, the stud memberis normally maintained in its normal latching position by thehook-shaped head of the stand-by latch lever, which isbiased to itslatching position. The reciprocable stud member is released to itsactuated position by the actuating members driving the actu: ator bar ina direction opposite to its bias, whereby the step on the actuator baris caused to drivingly engage the. leg of the stand-by latch lever andpivotally rotatethe lever, against its bias, to its release position.

In its normal, biased position the actuator bar stud engages theprojecting arm of the safety-latch lever and maintains it, againstitsbias, in a release position. Dis-.

lever does not latch the reciprocable stud member at this time, however,since the reciprocable stud memberis not in its overshoot position.

Release of the stud member for movement to its actuated'position alsoremoves it from engagement with the projecting arm of the actuatorlatching lever, thus permitting that lever to move under the force ofthe bias applied thereto to be in position to engage the actuating bar.

Following full displacement of the actuator bar and upon deactuation ofthe actuating member, the actuator bar is caused by its bias to traveltowards its normal biased position. After travelling a predetermineddistance and before it reaches its normal, biased position, the actuatorbar is latched by the engagement of the notched ear thereon by thehooked portion of the leg of the actuator bar lever. With the actuatorbar in this position the stand-by latch lever is released to pivotallyrotate to its latching position according to its bias.

I Reset means are then actuated to cause the reciprocable stud member totravel in a direction opposite to its bias. The reciprocable stud memberengages ramp faces on the stand-by latch lever and safety latch lever inthis succession, causing them to pivotally rotate out of its path untilit passes. The stud member is displaced past its normal latchingposition to an overshoot position, where it is latched by thesafety-latch lever to prevent movement to its actuated position.

The actuator bar remains latched against movement towards its unactuatedposition by the hooked portion on the actuator latch lever during thereset stroke of the reciprocable stud member, until the stud memberreaches its normal latched position. Thus, the actuator bar ismaintained in its actuated position until the stud is relatched.Further, the stud is doubly latched, first by the safety latch lever andthen by the stand-by latch lever, upon its return stroke to insure thatthe stud is latched upon the return stroke.

Upon reaching the normal latching position, the reciprocable stud memberengages the depending arm of the actuator bar lever, causing theactuator bar lever to pivotally' rotate against its bias to release theactuator bar. The actuator bar is thereby freed to travel to its normalrest or unactuated position. In the course of this travel the actuatorbar stud engages the projecting arm of the safety latch lever causing itto pivotally rotate against its bias to release the reciprocable studmember from its overshoot position. The reciprocable stud member thenmoves to its normal latching position under its bias, where it isrelatched by the stand-by latch lever.

Accordingly, a primary object of this invention is to provide a latching.mechanism which prevents multiple reciprocations of a longitudinallyreciprocable member.

Another object of this invention is to provide a latching mechanism inwhich an actuating arrangement is retained in an actuated position whilea reciprocable memberis unlatched.

Yet another object of this invention is to provide a latching mechanismin which a reciprocable member is temporarily latched in an overshootposition upon resetting thereof to an unactuated or rest position.

"A further object of this invention is to provide a latching .mechanismwhich preventsmultiple reciprocations of a longitudinally reciprocatingmember which is particularly useful in connection with an articlevending machine to prevent the multiple vending of articles withoutproper payment therefor.

These and other objects, advantages and features of the subjectinvention will hereinafter appear and, for purposes'of illustration, butnot of limitation, an exemplary embodiment of the subject invention isshown in the appended drawing.

., BRIEF DESCRIPTION OF THE DRAWING FIGURE 1 is a top plan view of apreferred embodiment of the latching mechanism of the present invention4' in which a longitudinally reciprocating member is in its normallylatched position.

FIGURE 2 is a top plan of the latching mechanism illustrated in FIGURE 1and depicts the longitudinally reciprocable member released to itsactuated position.

FIGURE} is a top plan 'view of the latching mechanism illustrated inFIGURE 1 and depicts the longitudinally reciprocable member still'in itsactuated position but with the latching mechanism in a configuration toprevent further reciprocation of the member.

FIGURE 4 is a top plan view of the latching mechanism illustrated inFIGURE 1 and depicts the longitudinally reciprocable member in theovershoot position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The latching mechanismof this invention may be utilized in many environments, but for thepurposes of this application it shall be described in the context of anArticle Vending Machine claimed in an application filed concurrentlyherewith in the names of A. G. Bodoh, O. J. Schwertfeger, and R. A.Johnson, and assigned to the same assignee as the instant application.The Article Vending Machine application is directed toward anarrangement in which articles to be dispensed are located in areciprocably movable tray which is displaced to a vend position forvending of a selected article. After the selected article has beendispensed the tray is reset. During the reset motion the tray is drivenbeyond its normal latched position to an overshoot position beforereturning to the normal latched position.

A lock-out mechanism is drivingly engaged by a sliding actuator toprevent vending more than one article at a time. To make the look-outmechanism effective it is necessary to hold the sliding actuator engagedwith the lock-out mechanism during the dispensing operation and untilthe tray is latched against further vending. Also it is desirable toprovide protection against multiple vending due to the tray not beingproperly latched on the reset stroke. By using the present invention,these and other advantages may be obtained by utilizing a stud member 4on the tray to interact with the latching mechanism of the presentinvention.

Referring to FIGURES l-4, a stand-by latch lever 6 has a triangularlyshaped head 8, a mounting arm 10, and a depending leg 12, with arm 10and leg 12 extending from a circular pivot mounting 13 on a pivot 22 atessentially ninety degrees from each other. Triangularly shaped head 8,has a generally right-triangle configuration, the sides being of unequallength, with the hypotenuse of the triangular perimeter providing a ramp9 (FIGURE 2) for cammingly engaging stud member 4. Mounting arm 10 isattached to the short side of the head, adjacent the right angle andaway from the vertex formed by the hypotenuse and the short side and hasa width at the head approximately one-half the length of the short sideof the triangle, so that the remainder of the short side of the triangleforms a hook face 11 (FIGURE 2) adapted to engage and latch stud member4. Circular pivot mounting 13 is attached to mounting arm 10 at its endaway from the head and leg 12 is attached to the pivot mounting in amanner such that it forms a generally right angle with respect tomounting arm 10.

Stand-by latch lever 6 is biased for pivotal rotation in acounter-clockwise direction by tension spring 24, one end of which isfirmly attached to mounting arm 10 at a point 25 intermediate its ends.Stand-by latch lever 6 normally assumes its biased position, in whichbook face 11 is in the path of stud member 4 to engage and latch it inits normally latched position (FIGURE 1) and thereby prevent movement ofstud 4 to an actuated position (FIG- URE 2). Stud member 4 is normallybiased toward its actuated position (indicated schematically in FIGURESwise direction to the FIGURE 2 position against the force of bias spring24, causing triangle-shaped head 8 and mounting arm to similarlypivotally rotate in a clockwise direction, stud member 4 is released tomove to its actuated position under the force of spring 2. When latchlever 6 is released, the bias of spring 24 causes lever 6 to rotate tothe normal latching position. Return of stud 4 toward its normallylatched position brings it into en gagement with ramp 9 of latch lever 6to cause latch lever 6 to pivotally rotate against the bias of spring24, in a clockwise direction, whereby the head 8 is temporarily drivenout of the path of stud member 4, by the stud member 4, permitting thestud member to continue its travel to an overshoot position (FIGURE 4).After stud 4 passes the head '8 on its way to its overshoot position,the biasing force of spring 24 immediately returns stand-by latch lever6 to its normal latching position. This configuration is illustrated inFIGURE 4.

A safety latch lever 14 is illustrated (FIGURES 1-4) as having atriangularly shaped head 16, a mounting arm 18, a circular pivotmounting 19, and a depending leg 20. Triangularly shaped head 16 has agenerally right triangle configuration whose sides are of unequal lengthwith the hypotenuse providing a ramp for cammingly engaging stud member4. Mounting arm 18 is attached to the short side of the triangularlyshaped head, adjacent the right angle and away from the vertex formed bythe hypotenuse and the short side, and has a width approximatelyonelialf the length of the short side of the triangle so that theremainder of the short side forms a hook face 17 adapted to engage studmember 4. Circular pivot mounting 19 is attached to mounting arm 18 atits end away from head 16, and leg 20 is attached to mounting arm 18 ata generally right angle with respect thereto. Leg 20 extends ingenerally the same direction as leg 12 of stand-by latch lever 6. Safetylatch lever 14 is pivotally mounted on pivot 22, in common with stand-bylatch lever 6 in a scissors fashion. Lever 14 is biased for pivotalrotation in a clockwise direction by tension spring 24, one end of whichis firmly attached intermediate the ends of mounting arm 18 at a point21. The other end of spring 24 is firmly attached to mounting arm 10 ofstand-by latch lever 6, as previously described.

Safety latch lever 14 is normally held in a release position while studmember 4 is latched in its normally latched position by stand-by latchlever 6. After stud 4 is unlatched by stand-by latch lever 6, safetylatch lever 14 is freed to rotate into a position to latch stud 4 byspring 24. Of course, stud 4 is not in position to be latched, but asstud 4 is returned beyond the latched position it engages ramp 15 oflever 14 and causes it to rotate out of the way until stud 4 can pass.Immediately after stud 4 passes the end of latch 14, spring 24 returnslatch 14 to the latch position so that stud member 4 will be latched inthe overshoot position. Lever 14 is subsequently rotatedcounter-clockwise to release stud 4 so that it will move to engage latchlever 6 and be latched in the latch position.

A pivoted generally U-shaped actuator latch lever 32 has a bight 34 andtwo legs, 38 and 40, respectively. A triangularly shaped foot 42 has agenerally right-triangle configuration with the hypotenuse providing aramp 39. Foot 42 is attached to the end of leg 38 away from the bightalong a side of the triangle adjacent the right angle. The width of leg38 is less than that of the side of the triangle to which it isattached, so that the remainder of the side forms of hook face 43. Legis attached to the end of bight 34 away from leg 38 and extendsgenerally in the direction of stud member 4 in its overshoot posi tion.A depending foot 44, having generally the configura tion of atrapezoid,'is integrally formed with the end of leg 40 away from bight34. A notch face of foot 44 is adapted to engage stud 4, and end 47 offoot 44 is formed with an angular slope to act as a cam to pivot lever32 when stud 4 is engaged therewith. Actuator latch lever 32 ispivotally mounted for pivotal rotation about pivot 46, which passesthrough pivot mounting 48 attached to the bight 34 of actuator latchlever 32. Actuator latch lever 32 is normally biased in acounter-clockwise direction by a spring 50.

An actuator bar 30 is slidably mounted for longitudinal reciprocation onmounting member 50. Actuator bar 3t] is biased toward its normalunactuated position by a bias member (shown schematically as a tensionspring 68 in FIGURES 1-4).

Actuator bar 30 has a body portion 52 and a T-shaped head portion 53attached to the end of body portion 52 adjacent latch levers 6, 14 and32. A base 54 of the T- shaped head portion 53 is of smaller width thanthe body portion 52 and offset therefrom in a direction away from thelatch levers 6 and 14 so that the remainder of the end of the body 52forms a step 56. Step 56 is adapted to drivingly engage leg 12 ofstand-by latch lever 6 when the actuator bar is actuated, to causestand-by latch lever 6 to pivotally rotate in a clockwise direction,whereby hook 11 is rotated out of engagement with stud member 4 torelease stud 4 for movement to its biased vend actuated position.

A crosspiece 58 of the T-shaped head portion 53 is attached to the endof base 54 adjacent the latch levers. A depending arm 60 of thecrosspiece away from the levers has a rounded top arm portion 62 adaptedto cammingly engage ramp 39 of actuator latch lever 32 when actuatorlatch lever 30 is actuated, whereby foot 42 is pivotally rotated out ofthe path of actuator bar 30 on its actuating stroke. The bottom of thedepending arm 60 makes generally a right angle with base 54 so that alatching face 64 is formed. Latching face 64 is adapted to engage book43 of actuator latch lever 32 when stud member 4 is unlatched (FIGURES 3and 4).

An upwardly projecting actuator bar stud 66- is attached to the righthand arm 61 of the crosspiece 58 of the T-shaped head portion. The stud66 is adapted to drivingly engage leg 20 of safety latch lever 14whereby safety latch lever 14 is caused to pivotally rotate in acounter-clockwise direction which rotates hook 17 out of engagement withstud 4 and frees stud 4 to travel to its normally latched position(FIGURE 1).

Prior to actuation of actuator bar 30, actuator latch lever 32 isdisengaged from actuator bar 30, and stud 4 engages notch face 45 onfoot 44 of actuator latch lever 32, whereby the actuator latch isnormally maintained in a position wherein hook face 43 is not positionedto latch actuator bar 30. In this unlatched state, stud 66 on actuatorbar 30 engages leg 20 of safety latch lever 14 and holds lever 14 in theunlatched position. Bias spring 24 holds stand-by latch 6 in the latchposition.

Upon actuation stud 66 is removed from engagement with leg 20 of lever14, but the end of book surface 17 bears against stud 4 and is preventedfrom moving. Further displacement of the actuator bar 30 caused roundedtop arm portion 62 to cammingly engage ramp 39 on foot 42 to pivotallyrotate actuator latch lever 32 against its bias, in a clock-wisedirection, and foot 42 is temporarily driven out of the path of actuatorbar 30, permitting the actuator bar 30 to be driven by the actuatingforce to its actuated position (shown in FIGURE 2). Still furtherdisplacement of actuator bar 30 results in step 56 on bar 30 engagingleg 12 of latch 6 to drive the latter to unlatch the stud member 4 formovement to its actuated position, whereby stud member 4 disengagesnotch face 45 of actuator latch lever 34 and the biasing force on theactuator latch lever causes it to pivotally rotate in acounter-clockwise direction moving the foot 42 into the path of theactuator member. Upon deactuation of actuator bar 30, it is driventowards its normal biased or rest position by a biasing force actingthereupon. After a partial displacement in this direction, actuator bar30 is intercepted and latched against further displacement by hook 43 ofactuator latch lever 34 which engages latching 7 surface 64. Thispartial displacement is sufficient to per mit leg 12 of stand-by latchlever 6, although it is still engaged by the actuator bar, to pivotallyrotate, according to its bias, in a counter-clockwise direction wherebyhook 11 of stand-by latch lever 6 is rotated into the path of studmember 4 (FIGURE 3).

A reset arrangement (not shown) is then actuated to drive the studmember 4 against its bias from its actuated position to its overshootposition. As hereinbefore described, the stud 4 cammingly engagesstand-by latch lever 6 and safety latch lever 14 on this return strokeand each is immediately returned to its latching position afterdisengagement by the stud, to prevent movement of the stud to itsactuated position. Actuator bar 30 remains latched against movementtowards its biased, unactuated position by hook face 43 of actuatorlatch lever 32 during the return stroke of stud 4 until the stud memberreaches its overshoot position, wherein it is latched by hook face 17 ofsafety latch lever 14. Thus, until the stud 4 reaches its overshootposition, the actuator bar is restrained from re-engaging leg 20 ofsafety latch lever 14 to cause it to pivotally rotate to its releaseposition. Since stud 4 is latched, in its overshoot position, againstmovement toward its actuated position by safety latch 14, and actuatorbar 30 is latched against return to its rest position by actuator latchlever 32 multiple reciprocations of stud 4 cannot occur. When stud 4 isdriven to its overshoot position, it drivingly engages notch face 45 ofactuator latch lever 32 and causes the actuator latch lever to pivotallyrotate, against its bias, in a clockwise direction, whereby the hookface 43 of actuator latch lever 32 is rotated out of engagement withactuator bar 30 and the actuator bar is released to travel to its normalbiased or rest position. This configuration is illustrated in FIGURE 4.On its return stroke, actuator bar 30 drivingly engages leg 20 of safetylatch lever 14 and causes it to pivotally rotate, against its bias, in acounter-clockwise direction, whereby hook 17 of safety latch lever 14 isrotated out of engagement with stud member 4 and the stud member isfreed to move to its normal latching position wherein it is latched byhook 11 of stand-by latch lever 6. Thereupon, the configurationillustrated in FIG- URE 1 is again assumed and the arrangement is in aposition to perform another cycle of operation.

It should be recognized that the embodiments described herein are merelyexemplary of the present invention and that various changes,modifications, and variations may be made in the arrangements,operations, and details of construction of the elements disclosedherein, without departing from the spirit and scope of the presentinvention.

What I claim is:

1. A latching arrangement for a reciprocable member biased to anactuated position and returned from the actuated position by a suitabledriving arrangement comprising:

,a first latch means adapted to normally latch tne reciprocable memberin a first retracted position;

a second latch means adapted to latch the reciprocable member in asecond retracted position; and

an actuator member adapted, upon energization thereof, to cause saidfirst latch means to release the reciprocable member for movement to theactuated position, and whereby return of the reciprocable member to thesecond retracted position causes the reciprocable member to betemporarily latched in said second retracted position by said secondlatch means prior to relatching of the reciprocable member in said firstretracted position by said first latch means.

2. A latching arrangement as claimed in claim 1 and further comprising athird latch means biased to engagement with said actuator member butnormally disengaged therefrom, said third latch means being adapted tolatch said actuator member following the release of the reciprocablemember by said first latch means and to release said actuator memberupon the return of the reciprocable member to said second retractedposition.

3. A latching arrangement as claimed in claim 2 wheresaid first latchmeans comprises a first pivoted lever having a latching surface and anextending leg; said second latch means comprises a second pivoted leverhaving a latching surface and an extending leg, said latching surfaceson said first and second levers being adapted to engage the reciprocablemember; said third latch means comprises a third pivoted lever having alatching surface and an extending leg; said actuator member has anotched ear thereon adapted to be engaged by said latching surface onsaid third lever to latch said actuator member in its actuated position;said extending leg of said third lever has a projection thereon adaptedto engage the reciprocable member to be actuated thereby to rotate saidthird lever and prevent engagement of said latching surface thereon Withsaid notched ear on said actuator member; said actuator member has astep formed thereon adapted to engage said extending leg on said firstlever to rotate said first lever and prevent the latching surfacethereon from engaging the reciprocable member; and said actuator memberhas a stud connected thereto adapted to engage said second lever torotate said first lever and prevent the latching surface thereon fromengaging the reciprocable member. 4. A latching arrangement as claimedin claim 2 wherer in said third latch means comprises:

a first leg having a triangularly-shaped head portion and a mounting armextending from one side of said portion, said arm having a widthsubstantially less than the length of said side of said head portion sothat the remainder of said side forms a hook surface;

a bight portion attached to the end of said first leg away from saidhead portion;

a pivot mounting extending through said bight portion,

at a point intermediate its ends;

a second leg attached to the end of said bight portion away from saidfirst leg; and

a projecting arm attached to the end of said second leg away from saidbight portion.

5. A latching arrangement as claimed in claims 1 or 2 wherein said firstand second latch means comprise hooked levers pivoted about a commonpivot point and biased toward each other in a scissors fashion, adaptedto permit engagement and disengagement thereof by said actuator member.

6. A latching arrangement as claimed in claims 1 or 2 wherein said firstand second latch means comprise hooked levers pivoted about a commonpivot point and biased toward each other in a scissors fashion, and eachof said hooked levers comprises:

a triangularly shaped head portion;

a mounting arm extending from one side of said head portion, said armhaving a width substantially less than the length of said side of saidhead portion so that the remainder of said side forms a hooking surface;

a pivot mounting extending through the end of said mounting arm awayfrom said head portion; and

a depending leg portion projecting at an angle with respect to saidmounting arm and adapted to engage said actuator member.

7. A latching arrangement as claimed in claims 1 or 2 wherein saidactuator member is mounted for longitudinally reciprocable movement andcomprises:

a T-shaped head portion, one arm of the crosspiece of said T-shaped headportion forming a notched ear adapted to be engaged by said third latchmeans; stud mounted on the arm of the crosspiece of said T-shaped headportion away from said notched ear and extending outwardly from saidactuator member, said stud adapted to engage said second latch means tocause said second latch means to release the reciprocable member fromits second retracted position; and mounting arm extending from the endof the leg of said T-shaped head portion and having a widthsubstantially greater than that of said leg so that a step is formed atthe junction of said mounting arm and said base, said step being adaptedto engage said first latch means to cause said first latch means torelease the reciprocable member from its first retracted position.

References Cited UNITED STATES PATENTS 5/1966 Johnson et a1 221125 X7/1968 Phillips et a1. 221--125 STANLEY H. TOLLBERG, Primary Examiner

